Fostex TH900 Impressions & Discussion Thread
Nov 21, 2014 at 12:53 AM Post #8,207 of 18,759
Left channel isn't working on my TH900 after I gave them a good clean, any advice would be much appreciative.........HELP!!
 
So I decided to clean TH900s mainly because the pads have been flaking that black compressed eggshell off the pads, after 2 years of everyday use. I used a Festool CT36 non-static airflow vacuum, the airflow adjusted just enough to pull off loose flakes, the rest came off using my fingernail with vacuum nozzle close by.
 
I really can't understand how this could damage the driver but something has gone wrong obviously. Right channel is fine, Left channel isn't completely dead just very quiet
 
Any suggestions would be very much welcome....
 
Nov 21, 2014 at 1:18 AM Post #8,208 of 18,759
  Left channel isn't working on my TH900 after I gave them a good clean, any advice would be much appreciative.........HELP!!
 
So I decided to clean TH900s mainly because the pads have been flaking that black compressed eggshell off the pads, after 2 years of everyday use. I used a Festool CT36 non-static airflow vacuum, the airflow adjusted just enough to pull off loose flakes, the rest came off using my fingernail with vacuum nozzle close by.
 
I really can't understand how this could damage the driver but something has gone wrong obviously. Right channel is fine, Left channel isn't completely dead just very quiet
 
Any suggestions would be very much welcome....

The only time that's ever happened to me was when I used a wet cloth to clean my T90s. One channel became quiet. It slowly started to get better after a few hours. The next day it was back to normal. Did you use a wet cloth? 
 
Nov 21, 2014 at 1:33 AM Post #8,209 of 18,759
  The only time that's ever happened to me was when I used a wet cloth to clean my T90s. One channel became quiet. It slowly started to get better after a few hours. The next day it was back to normal. Did you use a wet cloth? 

I did notice oil build up on the pads themselves, I put this down to years of use which is kind of disgusting when you think about it, but unless it's on the driver itself I can't really seeing it being a problem.
 
I think I'm just going to have to pull it apart and see what's going on
 
Nov 21, 2014 at 3:15 AM Post #8,210 of 18,759
  Left channel isn't working on my TH900 after I gave them a good clean, any advice would be much appreciative.........HELP!!
 
So I decided to clean TH900s mainly because the pads have been flaking that black compressed eggshell off the pads, after 2 years of everyday use. I used a Festool CT36 non-static airflow vacuum, the airflow adjusted just enough to pull off loose flakes, the rest came off using my fingernail with vacuum nozzle close by.
 
I really can't understand how this could damage the driver but something has gone wrong obviously. Right channel is fine, Left channel isn't completely dead just very quiet
 
Any suggestions would be very much welcome....

 
Unmount the pads (by rotating counter clockwise), then take off the cups. Check the cable connection first, though probably not the problem, so indeed check the drivers. My hunch is that the membrane was dislocated and stuck because the air pressure and you'd need to get it unstuck. Hopefully the coil wasn't damaged.
 
Nov 21, 2014 at 5:34 AM Post #8,211 of 18,759
  Left channel isn't working on my TH900 after I gave them a good clean, any advice would be much appreciative.........HELP!!
 
So I decided to clean TH900s mainly because the pads have been flaking that black compressed eggshell off the pads, after 2 years of everyday use. I used a Festool CT36 non-static airflow vacuum, the airflow adjusted just enough to pull off loose flakes, the rest came off using my fingernail with vacuum nozzle close by.
 
I really can't understand how this could damage the driver but something has gone wrong obviously. Right channel is fine, Left channel isn't completely dead just very quiet
 
Any suggestions would be very much welcome....


 Sorry to hear this Gandah.  As mentioned earlier by zolkis it does sound as if something happened to the membrane during "vacuuming".
 
It cant hurt to remove the cup and give it a visual, otherwise I see a trip to Tokyo in their future.  On the bright side of things Foster Japan is very quick and thorough especially in communicating with you and keeping you updated.
 
After all is said and done if they require work you may be without them for 2 weeks max.
 
Cant hurt to email them with questions support@kotori.fostex.jp  they will follow up with you most likely within 24 hours or less.  Best of luck in getting it sorted out. 
 
Nov 21, 2014 at 7:22 AM Post #8,212 of 18,759
   
Unmount the pads (by rotating counter clockwise), then take off the cups. Check the cable connection first, though probably not the problem, so indeed check the drivers. My hunch is that the membrane was dislocated and stuck because the air pressure and you'd need to get it unstuck. Hopefully the coil wasn't damaged.

 
 
 Sorry to hear this Gandah.  As mentioned earlier by zolkis it does sound as if the something happened to the membrane during "vacuuming".
 
It cant hurt to remove the cup and give it a visual, otherwise I see a trip to Tokyo in their future.  On the bright side of things Foster Japan is very quick and thorough especially in communicating with you and keeping you updated.
 
After all is said and done if they require work you may be without them for 2 weeks max.
 
Cant hurt to email them with questions support@kotori.fostex.jp  they will follow up with you most likely within 24 hours or less.  Best of luck in getting it sorted out. 


Thanks guys I appreciate your input,
 
Getting the white plastic ring off OMG!! was a nightmare to do, in the end I ended up taking the pad off first than the ring, I will do the rest tomorrow as I want to see it in natural light. I will keep you updated maybe with pic's if I'm not sure what to look for.
 
Thanks again.....
 
Nov 21, 2014 at 7:55 AM Post #8,213 of 18,759
 
Getting the white plastic ring off OMG!! was a nightmare to do, in the end I ended up taking the pad off first than the ring, I will do the rest tomorrow as I want to see it in natural light.

 
Ideally one should first make a tool for this (like a strong wire bent to match the holes and then mounted on a rigid holder) or use one. I used an existing generic tool I've had, but indeed I got the pads off the white holders first, then unmounted the pad holders themselves. First time is the hardest because the plastic edges are rough; after that it goes much easier, clicks in and out much more smoothly (which I guess was the original idea).
 
Nov 21, 2014 at 9:10 PM Post #8,214 of 18,759
Well just a call out for getting my cable mod for my th900. After getting an alo quad ribon for my 846 and getting blown away by that extra pipe, i decided to go for black scorpian lawton mod. Course sending down for marc to do it, let you all know the outcome in a few weeks. Here here for better pipe.
 
Nov 21, 2014 at 9:39 PM Post #8,215 of 18,759


So visually I can't see anything wrong with it, but I'm also really unsure what to look for. It could be the cable or the connector, I tried wiggling the jack and cable to see if there was a brake in the cable or in the jack however there was no change in sound to the driver just very quiet, so I'm kind of stamped 
confused.gif
 
 
Nov 21, 2014 at 11:46 PM Post #8,216 of 18,759
Does the driver look too forward compared to the other side? Has it been raised up/dislodged? If so, maybe you can tap the rear of the driver/baffle on the table and knock it back? Don't quote me on that.
 
Nov 22, 2014 at 7:01 AM Post #8,217 of 18,759
Does the driver look too forward compared to the other side? Has it been raised up/dislodged? If so, maybe you can tap the rear of the driver/baffle on the table and knock it back? Don't quote me on that.


It's really hard to see or get too with the metal grill in the road, at this point I think I will be better off sending them to Japan for repair
 
Note to self, never clean headphone pads with them attached to the drivers.......... My bad
blink.gif

 
Nov 22, 2014 at 8:51 AM Post #8,218 of 18,759
 

So visually I can't see anything wrong with it, but I'm also really unsure what to look for. It could be the cable or the connector, I tried wiggling the jack and cable to see if there was a brake in the cable or in the jack however there was no change in sound to the driver just very quiet, so I'm kind of stamped 
confused.gif
 

That is exactly the design of the old Denon (D2000/D5000/D7000) drivers. I think the actual cone material is different but the design is exactly the same.
 
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Nov 25, 2014 at 4:34 AM Post #8,219 of 18,759
 

So visually I can't see anything wrong with it, but I'm also really unsure what to look for. It could be the cable or the connector, I tried wiggling the jack and cable to see if there was a brake in the cable or in the jack however there was no change in sound to the driver just very quiet, so I'm kind of stamped 
confused.gif
 


 Any progress Gandah?
 
Nov 25, 2014 at 5:47 AM Post #8,220 of 18,759
 
 Any progress Gandah?

Yeah thanks man, I have them boxed and ready to be taken to Fostex HQ Australia, which fortunately is located here in Sydney just down the road, so hopefully they have the parts on hand and won't take too long. I don't know how it works, if you have to buy a matching pair or if they match the driver up with the existing one, but in any case  I'm going to ask to replace both drivers
 

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